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Emission Control

Pyrolisis & Gasification

Pyrolysis & gasification are both thermal decomposition processes. Pyrolysis occurs in the full absence or near absence of oxygen, leading to the production of solid, liquid, and gaseous products, whereas gasification occurs in a partial absence of oxygen, primarily producing syngas. Both processes can convert organic materials into valuable products and can be used for energy production.

Applications include:

Biochar Production: Biomass is thermally decomposed in an oxygen-limited environment to produce biochar, used for soil enhancement and carbon sequestration, improving soil health and reducing greenhouse gases.

Activated Carbon: Organic materials are processed to produce activated carbon, which has high surface area and is used for water purification, air filtration, and in medical applications.

Waste to Minerals: Processes like paper sludge pyrolysis recover valuable minerals, e.g., calcium carbonate, which can be reused in consumer products, reducing waste and promoting recycling initiatives.

Waste to Energy: Converts municipal and industrial waste, including sewage sludge,  meat and bone meal and other animal and forestry wastes, into energy-rich syngas or bio-oil, reducing landfill use and generating renewable energy. Animal by-products can be transformed into sterilized, nutrient-rich char, which can be used as fertilizer or as a renewable fuel.

The Role of Cyclones in Pyrolisis & Gasification Processes and Carbon Capture

BECCS - Bioenergy with carbon capture and storage is the process of using biomass, such as trees, crops, or residues, for energy production through pyrolysis & gasification processes with very low O2, while capturing the carbon in a solid form (dust) before it is released into the atmosphere.

Dedusting after these high temperature processes has always been a very good application for cyclones since these can separate particulate matter (PM) from very hot air streams with reduced pressure drop, negligible downtime and low CAPEX and OPEX.

Furthermore, the CO2 in the flue gases can also be captured by several alternative means such as by the injection of solid sorbents e.g. hydrated lime, or calcium oxide (CaO). The product of the reaction from CO2 and CaO, known as “carbonation”, is solid Calcium Carbonate (CaCO3) and cyclones are ideal to capture it.

METHANE PYROLYSIS

Methane pyrolysis is a process where methane is thermally decomposed under high temperatures without oxygen to produce clean hydrogen and solid carbon separated with cyclones. This technology is seen as a bridge to a low CO2 future, enabling the production of clean energy at a large scale. The solid carbon by-product can be used in various industries, thereby offsetting emissions from public works projects and contributing to a more sustainable environment. Methane from natural gas or biogas is converted, reducing CO2 emissions and supporting the future energy systems without direct CO2 emissions.

Source of original scheme: Modern Hydrogen
 
For these very high temperature exhaust streams (>600ºC) the general arrangement of the plants include cyclones and/or heat ceramic filters followed by heat exchangers, after which traditional bag filters or scrubbers are used as end stage dedusters.
The primary high temperature separator, typically a cyclone, needs to reduce ash and recovers the carbon based product. A good efficiency is important for the product yield and to diminish concentration of solids to end stage dedusters, avoiding plugging of scrubbers and damaging of filters. Ceramic filters are an option but have a considerable pressure drop, typically up to 300mm w.g., gradually increasing due to clogging of the pores. The long-term durability and cracking risk (mainly during cleaning) of the elements are also critical.

The primary high-temperature separator, often a cyclone, aims to minimize ash content while maximizing recovery of char, typically in the form of a carbon-rich byproduct such as biochar. Achieving high efficiency in this process is crucial for maximizing product yield and reducing the concentration of solids in the downstream end-stage deduster, thereby preventing blockages in scrubbers and damage to filters. While ceramic filters are an alternative, they present a significant pressure drop, typically up to 300 mm w.g., which tends to increase over time due to the clogging of pores. Additionally, the long-term durability and susceptibility to cracking, especially during cleaning, of these elements must be considered.
 
At low temperatures, traditional bag filters imply the frequent change of bags and often disturb the continuity of syngas production with the need to clean the filtering elements. Bag filters incur operational costs and can lead to production downtime.

Clients require a robust and efficient high-temperature pre-separation in the initial stage, coupled with an extremely efficient final-stage dedusting system located upstream of the engine or recovery boiler, characterized by low operating expenses (OPEX).

To meet these needs, ACS offers solutions such as hot cyclones positioned immediately after the gasifier and high-efficiency cyclones as alternatives to scrubbers and bag filters, especially suitable when the gas streams have low particulate concentrations.

For detailed insights and results, we invite you to explore our case studies across various industrial segments.